<!DOCTYPE HTML>
<div style="width:400px;">
  <span style="opacity:0.5;">
    <span style="position:relative; display:inline-block; width:400px; height:200px;"></span>
    <span style="position:relative; top:-300px; display:inline-block; background:lime; width:400px; height:400px;"></span>
  </span>
</div>
